Abstract: ABSTRACTObjectives:Late-life depression, falls, and fall worry are public health problems. While previous research confirms the cross-sectional relationship between depression and fall worry, few longitudinal studies have examined whether changes in fall worry are associated with changes in depressive illness and vice versa. This study examined longitudinal relationships between probable major depression (PMD) and activity-limiting fall worry (ALW).Design, Setting, Participants, Measurements:This longitudinal panel observational study used data from the National Health and Aging Trends Study (NHATS) waves 5 (referred to as T1 in this study) and 6 (T2), conducted in 2015 and 2016, respectively (N = 6,299, aged 65 and older). We examined associations of new and continued ALW between T1 and T2 with T2 PMD, controlling for T1 PMD; and associations of new and continued PMD between T1 and T2 with T2 ALW, controlling for T1 ALW. We used ?2 and t tests for descriptive statistics and logistic regression for multivariable analysis.Results:Those with new ALW at T2 had significantly greater odds of T2 PMD compared to those without ALW at both time points (AOR = 2.64, 95% CI = 1.98-3.51), and those with new PMD at T2 had significantly greater odds of T2 ALW (AOR = 2.42, 95% CI = 1.66-3.52). Those with continued PMD also had greater odds of T2 ALW compared to those without PMD at either time point (AOR = 2.31, 95% CI = 1.62-3.29).Conclusions:The findings add to knowledge about bidirectional (mutually reinforcing) relationships between depression and activity-limiting fall worry. Innovative interventions are needed to reduce both late-life depression and activity-limiting fall worry.